The Enemy Within
by theDubliner
Summary: Reboot from an episode in TOS. When something goes wrong with the transporter, the captain is forced, quite literally, to face his darker half. With Sulu and others stranded on the surface of a soon-to-be frozen planet, and Jim's "evil" side roaming the halls of the Enterprise, what will it take for Spock to put the captain back together?
1. Chapter 1

_Author's Note: So after having discovered Star Trek via the new JJ Abrams' franchise, I decided to go back and watch the original series. This is, aptly, a reunion of the two. A reboot of an episode in the first season which shares its name with this story: "The Enemy Within". The plotline is almost directly derivative of that episode, but I have taken the more character-driven traits from the Abrams movies. I don't really wish to say more, lest I give away the plot. That being said, this was a little too long for a one shot, so I've divided it into three parts with the next installments coming soon. Please enjoy! And please leave some feedback, as I adore hearing from you guys!_

* * *

It was meant to be a routine mission to the planet Alpha 177; the objective being to discover and classify heretofore unidentified lifeforms. Pretty basic.

If there was one thing Captain James T. Kirk had learned in his yet early captaincy, however, it was that the "routine" missions were generally the ones that ended in the most unexpected and disastrous ways.

"I think it's a … a dog, sir? A space dog?" Lieutenant Sulu holds the fury pink creature in his arms, laughingly examining the long horn protruding from its forehead.

The captain laughs. "That should make a good specimen," he says jokingly.

The planet appears to be mostly devoid of any humanoid life forms, though its conditions are comparable to Earth's; the only exception being that the planet's orbit takes it so far from it's sun that overnight temperatures drop dangerously to almost one-hundred and twenty degrees below zero. Jim wanders for a few moments, watching his crew complete their assigned tasks. He cannot help but feel a solid, warm little ball of pride from within the center of his chest. They haven't been together very long – less than a year, really – and they are all impossibly, gloriously young for Starfleet officers. And yet, _and yet_, as far as Jim is concerned, they might have been the most decorated crew in the galaxy, aboard the most celebrated ship in the universe. Such was Jim's pride in the Enterprise and her crew.

"Captain?" Sulu interrupts his musings, "I think Fisher's been injured, sir."

Jim takes a look at the man's hand. "What happened, Lieutenant?"

The man flexes his fingers and uses his uninjured hand to dislodge a patch of yellow dust from his uniform. "Just took a fall, captain, into a patch of some debris over the other side of those rocks."

Jim nods. "Well it's not too bad, but the team's all but finished here. Why don't you have Mr. Scott beam you up early and you can head to sickbay to get patched up."

Fisher nods and relays as much to the ship's engineer before Jim hears Scotty's heavily-accented assent over the communicator.

"Sulu," the captain turns back to his helmsman, "good work today. I'm gonna go ahead and head back, make sure Fisher is seen to. You boys finish up here and contact Mr. Scott when you're ready to beam back."

"Aye aye, sir. Oh, and, uh, captain?"

Jim raises an eyebrow. "What's up, Sulu?"

The pilot looks sheepish for a moment, his grin almost embarrassed. "Permission to take the, uh, space dog back with us, sir?"

Jim's return smile is brilliant. It makes his job so easy, really, when making a crewman happy can be achieved so simply. "Granted," he chuckles, then adds as an afterthought, "But let's try to keep it quiet. Commander Spock might not find it entirely _logical_, our deciding to keep a pet…"

Lieutenant Sulu nods solemnly, as if he's only just realized the consequences of the Vulcan finding a dog on board the Enterprise, but there is a smile tugging at the corners of his mouth.

* * *

"Welcome back, Captain," Scotty smiles cheekily as Jim materializes on the transporter pad in front of him.

Jim nods his acknowledgement, but he feels himself stumble as he steps from the platform. He feels unbalanced, somehow, not quite himself…

"Steady on, Jim," Scotty says kindly, "let me give you a hand."

Jim shakes his head. "Just a little dizzy, Scott, I'm fine."

"You look pale. Let me take you to your quarters, Jim. You might do with a quick nip, sir."

And Jim nods, all thoughts of checking up on Fisher wholly abandoned. He doesn't question this sudden lack of initiative, doesn't wonder at the fact that it is very out of character for him to blindly obey another crewmember, especially when they are telling him to _rest_. No, usually Jim would scoff at such an implication, ever defiant. But he merely shakes his head again and mumbles good-naturedly, "Oh, Sulu's gonna beam back a dog, by the way. Consider yourself warned…" before allowing himself to be led from the transporter room.

* * *

On his return, Scotty is confronted with a very flustered fellow engineer. "You didn't tell me they were bringing _animals_ back with them," Wilson grumbles.

Scotty chuckles guiltily. "Right, yeah, a dog, isn't it? At Mr. Sulu's request."

"_Two_ dogs," Wilson clarifies, obviously irritated, "and one is a damned terror. Locked it in the basket for now. Crazy thing tried to bite me."

Scotty frowns. "I'm sure the captain only mentioned _one_ dog. Anything wrong with the transporter, Wilson?"

Engineer Wilson shrugs. "Suppose it was acting a bit funny. I beamed the first dog back, but the second came all on its own. I thought it was just a delayed trans-signal."

Scotty looks over his shoulder warily, studying the basket that shakes with the vicious growls of its imprisoned canine. And beside it, the other dog – pink and whimpering in fear, yet inexplicably unwilling to move away from its counterpart...

* * *

Jim is in his quarters, fresh from a shower, when his first officer makes his presence known from the corridor.

"Yeah," Jim calls, "come in, Spock."

And then there he is, standing tall in Jim's doorway, hands clasped behind his back, dark eyes shining with something that looks alarmingly like concern. It makes Jim sad, instantly, though he can't say quite why. That look of worry – worry for _him_ – renders Jim instantly guilty. He takes a step forward, ready to do whatever it takes to alleviate the worrisome lines on Spock's face. Jim can only describe this new, intense emotion as … protectiveness, perhaps.

"Is there anything I can do for you, Captain?"

Jim frowns. "Like what?"

"Dr. McCoy felt that I should check in on you, sir," Spock says, without further explanation.

"Oh?"

"Yes sir. He was quite concerned."

Jim shakes his head, trying to dispel the sudden, crippling feeling of guilt. He doesn't know _why_ Bones is worried – isn't sure what he's done this time to merit the good doctor's concern – but he knows he doesn't deserve it. Nor does he deserve the expression of care on Spock's face. They're both such good men, Spock and Bones, and Jim feels he must be the most selfish asshole alive to make them always-

"Captain?" Spock has taken another step forward. He thinks maybe the captain is inebriated. After all, Dr. McCoy _did_ say that Jim stole an entire bottle of brandy from him, earlier in the day. The doctor had described his demeanor then as aggressive – quite the opposite of the attitude Spock now observes. But he does not disclose this information to the captain. Not yet.

"I'm quite alright, Spock," Jim says, meeting his first officer's eyes sadly. His tone is polite, almost … apologetic. "You should go find Bones and tell him I'm fine. I'm just going to stay here." Jim sits down gingerly on his bed. "I'm just going to sit right here. Please don't worry. You look so … sad."

Spock visibly blanches. "A human emotion, captain," he says, testing.

But Jim does not respond in any way sarcastically or teasingly, as is his wont when his friend tries to deny the existence of his human half. Instead he … apologizes again.

"Of course, commander. I don't mean to be insulting." And he hangs his head.

* * *

When Commander Spock returns to sickbay, ready to report on his captain's overly emotional, highly illogical display, he is perplexed to find engineer Scott already complaining to Dr. McCoy of Jim's strange behavior. Yet the engineer's tale is completely contrary to his own … and, perhaps, far more disturbing.

"Bloody hell," Scotty winces, touching his already-swelling left eye. "But the captain's got one hell of a right hook."

Dr. McCoy curses under his breath. "Damn kid's gone off his rocker," he grumbles.

"Excuse me, Mr. Scott, but I must have misunderstood. You claim to have just come from an altercation in which your assailant was … the captain?"

McCoy interrupts Scotty's reply with a scoff. "Damnit, Spock, you don't _misunderstand_ much of anything. And you sure as hell didn't mishear, not with those freaky alien ears of yours. So what are you getting at? I thought you were going to check up on Jim?"

Spock ignores the doctor and turns, pointedly, to face Scotty instead. "Tell me what happened, Mr. Scott."

Scotty looks between doctor and first officer before clearing his throat uncomfortably. "I, uh, was down, back in the transporter room, waiting for Sulu and the others to request to beam back – I'd sent Wilson for lunch. And, uh, the captain comes in, looking all feverish and excited…"

"Probably drunk from all that damn brandy he took," McCoy grumbles bitterly.

Spock doesn't even spare him a glance as he waits for the engineer to continue.

"He wanted me to fight him," Scotty confesses, obviously confused and rather upset. "Said he hadn't had a good fight in ages – started hopping around like a madman with his fists up, trying to challenge me."

Spock raises an eyebrow. "The captain wished to fight you, Mr. Scott?"

"Aye, that's what I said."

"And by fighting the captain, just now, you have received these injuries. Is that correct?" Spock indicates Scotty's blackened eye, his split lip.

Scotty nods, but McCoy interrupts yet again. "Which wouldn't have happened if you'd just gone to check on him like I asked." The doctor's tone is bitter and accusatory, but Spock knows that it most often his method of concealing his fear for his friend. McCoy continues: "Where the hell were you, damnit, while Jim was beating Scott to a bloody pulp?"

Scotty raises a finger to interject, perhaps to deny having been beaten that badly, really, but what Spock says shuts them both up.

"I was in the captain's quarters … with the captain."

There is a long pause before Dr. McCoy manages to stop gaping stupidly at the Vulcan and mutter, "Well fuck me…"


	2. Chapter 2

_Author's Note: Hello again! It seems I just couldn't stay away. Not much to say here really, other than please enjoy this second installment complete with double helpings of our favorite Starfleet captain. Also, I do hope you understand why my "good" Kirk appears so much weaker than the "good" Kirk in TOS. In TOS, Kirk is a solid, well-rounded man. He has his faults, of course, but is generally the heroic ideal. The Kirk in Abrams' movie, however, appears far more damaged - even his best qualities remain plagued by a sense of guilt and self doubt. Anyway, just a few clarifying notes, as this section deviates a little more pointedly from the original episode - please forgive the liberties I have taken with the characters. _

* * *

"Now wait just one minute, Spock," Doctor McCoy interrupts, irritably, "What you're implying would have to mean that Jim was in two places at once?"

The looks on both his companions' faces are of the wildest disbelief, but Spock only nods once and says, "That would seem the only logical conclusion, doctor."

McCoy sputters for a moment before snapping back to the calm, confident man that lies beneath the layers of inane metaphors and practiced theatrics. Spock has always secretly admired this trait of the doctors' – indeed, he may act illogically a great majority of the time, but when it matters, his level head is invaluable in a crisis. "Well, if Mr. Scott's Jim was picking fights and stealing booze … what was _your_ Jim doing?"

Spock refrains from mentioning that the doctor's use of the possessive pronoun is inaccurate, as neither of the captain's current manifestations are his own personal property. Instead, he raises an eyebrow and says, hesitantly, "The captain appeared … conflicted."

"Conflicted?" This is Scotty, scooting forward on the exam table.

"Affirmative," Spock continues, "He seemed distressed that we had experienced feelings of concern for him; as a result, he resolved to stay in his quarters. I suspect this was an attempt to alleviate our worry. His demeanor was … docile, reserved, almost remorseful." Spock's forehead creases in consternation, and he concludes: "Suffice it to say, the captain was not himself."

McCoy sits down heavily in a chair beside his desk, his bewilderment and frustration plain on his face. And that is when Scotty pipes up to say, "It may have something to do with the dogs…"

* * *

A few moments later, standing in the transporter room, Scotty has Wilson explain about the two dogs and the mystery of their having beamed down separately, despite his only _intending_ to beam up a single animal.

"Fascinating," says Spock, taking a step towards the animals. "Two canines, perfectly identical but for their dispositions. One gentle, in full possession of its faculties – the other vicious, prey to its most base instincts."

"Dr. Jekyll and Mr. Hyde," Scotty jokes uneasily, his accent thick.

Spock cocks an eyebrow, but McCoy explains: "An old Earth fiction – pure good and pure evil."

Spock ponders the notion but McCoy is already dismissing it. "The two Jims aren't good and evil, though. The one's loud and, frankly, obnoxious, but the other just seems … weak."

Spock raises a finger. "We must consider, doctor, that these are not good and what you humans refer to as 'evil' traits in general, but rather good and evil traits as they pertain to the captain personally."

Doctor McCoy, for once, does not interrupt. He allows Spock to reach the culmination of his logic.

"What are the captain's best qualities?" the Vulcan asks pensively, steepling his fingers and slowly pacing the room. He answers his own question promptly. "Loyalty, a fierce protective nature, dedication, intelligence. And the captain's less desirable qualities? Recklessness, pride, defiance of authority-"

"Drunkenness," McCoy adds bitterly, still clearly upset over his pilfered brandy.

Spock raises an eyebrow, but does not disagree. He has seen the captain, occasionally, drink to excess. However, it is usually in response to some emotional upset – often, following the death of a crewmember, which Jim always takes as evidence of his own personal failings.

McCoy moans. "So bad Jim is basically acting the way he did back at the Academy. Drinking, picking fights…" then he lets out a bitter laugh, "God help us – lock up all the ship's women."

Spock ignores this last, but nods seriously. "Yes, the captain's disposition before he was given command, before he was forced to mature in order to undertake his new responsibilities. He will be volatile and needlessly unmanageable."

"So we've gotta get rid of bad Jim," Scotty offers, sounding doubtful.

"No," Spock says, a disappointed schoolmaster chiding a thoughtless pupil. "These traits are still present in the captain as we know him. His brashness has saved this ship on multiple occasions, has it not?"

McCoy smiles fondly, as if remembering. "Shoot first and ask questions later," he chuckles.

"Precisely," Spock says gently. "Without the captain's inherently bold nature – without his 'bad' side – he is merely the timid individual I encountered today in his quarters. Kind, and eager to please, and _good_, though incapable of commanding a starship."

"So … we kill good Jim?" Scotty says, sounding even more uncertain.

McCoy resists the urge to slap the back of the engineer's head. Spock cocks an eyebrow, the gesture alone conveying more than he could with words.

"No, Mr. Scott," McCoy interrupts. "We need them both. We just … need to find a way to get them back into one body."

Both engineer and doctor look to Spock as if he might be hiding the answer somewhere on his person.

Thankfully, the Vulcan is relieved of this responsibility as his communicator beeps on his hip. He raises it to his lips, "Spock here."

"_Commander,_" it is Lieutenant Uhura. "_Spock, I think you'd better come here. The captain's on the bridge, but I think … I think he might be drunk? He's, well, he's dancing, sir. On the bridge._"

Spock tries to hide his amusement. Of course his captain would find the most inappropriate place to perform the most inappropriate action… Then he stills for a moment as something catches his attention. "Lieutenant, what is that in the background?"

It's faint, over the comm. Perhaps only Spock's Vulcan hearing could have picked it up.

"_Old Earth music, sir. Jim had the computer pull up the, uh, the _Beastie Boys_, from the archive…_" Uhura's tone sounds scandalized.

Spock's memory is nearly absolute, which means he recalls, in perfect detail, the quiet night in his quarters when Jim first told him about destroying his stepfather's old topless automobile. The joyride that almost ended his captain's life before he'd even had a chance to bask in the man's brilliance – the feeling of flying, the glorious defiance of authority, of gravity – and the song that provided his reckless soundtrack. Spock almost smiles at the fond recollection.

"Dr. McCoy is on his way, Lieutenant. Please refrain from eliciting any negative emotions from the captain at this time. He is unwell. Do not-"

But Uhura is suddenly yelling. Though she has obviously dropped her communicator, Spock can still hear the music and the voices from the bridge.

"_Aw, c'mon Chekov – maximum warp – I wanna go _fast_!_"

Then Uhura's voice again, "_Captain, sir, you can't just take the Enterprise joyriding-_"

"_That's an _order_, Chekov_."

And the helmsman's timid refusal: "_Vee still have crewmen on ze surface, captain … Lieutenant Sulu, sir…_"

"_Damnit, why am I the only one who likes _fun_ on this goddamn ship? … C'mere, Uhura, dance with me!_"

Spock shuts his communicator, having heard more than enough of the conversation. "Dr. McCoy, kindly report to the bridge and restrain the captain."

McCoy chuckles, mumbles a "Not likely," but obeys all the same.

"Mr. Scott, you will remain here and fix that transporter. Not only are we unable to restore the captain, but we may not retrieve Lieutenant Sulu and the others until your task is complete."

Scotty chuckles. "So no pressure."

The Vulcan ignores this last and straightens his uniform.

"And where will you be, commander?"

Spock tilts his head to the side. "I must find the … the _other_ captain, and inform him of the existence of his secondary … self."

* * *

When Spock returns to the captain's quarters, it is to find his friend sitting on the bed, an old album of Terran photographs open upon his knees. As such media is generally stored on the computer, Spock concludes that the contents of the album must be sentimental in nature.

"Spock," Jim looks up from the album and his smile is radiant. It is not the crooked, mischievous grin that the captain so often wears, but a simple smile – pure and full of joy at finding his friend in his doorway.

"Captain," Spock inclines his head.

"Come here, Spock."

Spock knows that there really isn't time. He is also aware that taking advantage of Jim's overly emotional state is not … morally praiseworthy. Yet he cannot help but sit where his captain has instructed and lean his head over Jim's shoulder to see what his friend might wish to show him.

They are pictures of his father – Spock might have guessed as much – obviously compiled by Winona Kirk back on Earth.

"I never knew him, obviously," Jim begins, "but the way my mom talked about him … well, it _felt_ like I knew him."

Spock looks on, his face impassive.

"When I was a little boy, I used to wish it had been anyone else who took command of the Kelvin – anyone else's father who died." Jim's eyes are wet and slightly reddened. "How fucking selfish, right?"

Spock hesitates only a moment before laying his hand on his captain's shoulder, knowing that physical touch is often a comfort to humans.

"I wanted to know him _so bad_," Jim confesses, staring intently at the photos. "And if I couldn't know him, I … I wanted to _be_ him."

Spock tilts his head to one side. Nothing in Jim's confession is unknown to him, and yet, to actually _hear_ the words … Spock shifts uncomfortably.

And then Jim looks up at his first officer, and he looks … tragic.

"You're a good friend, Spock," he says sadly.

And while the jump from one subject to another, seemingly without reason, is slightly disconcerting to Spock, he warms at Jim's proclamation.

"I know you didn't always like me," Jim continues, "But I always thought you were wonderful. You're so much … _better_. You – you'd make twice the captain I am, Spock, I-"

Spock stands abruptly, knowing he has trespassed too far into his friend's delicate subconscious. "Captain, there is something I must tell you. I apologize for my delay; it was, regrettably, selfishly motivated and illogical. However, I must stop you now. You would not ordinarily be so free with your speech, nor would you so openly express this self doubt. It is only your current lack of pride, and the temporary loss of your more … difficult attributes that makes you speak so."

Jim shakes his head, baffled.

"You are a good captain, Jim," Spock says simply. "You will remember that once we have managed to restore you to your proper self."

"I – I don't understand, Spock."

And so Spock explains, as precisely as he can, the existence of the "other" captain, as well as McCoy's theory that the two are manifestations of the good and evil halves of the same man. "This would explain your current emotional state, as well as your reluctance to leave your quarters and retrieve command. You do remember, do you not, that Lieutenant Sulu and three other crewmen remain on the planet's surface?"

Jim looks frightened, pained, but the reminder of his crew steadies his features fractionally.

Spock continues. "We are unable to retrieve the men, for fear they will undergo similar consequences. In the interim, your alternate self is wandering the Enterprise causing havoc."

Spock notes the terrified expression on Jim's face, but does not cease in his entreaty.

"Captain, Scotty is attempting to rectify the transporter malfunction. Until he is successful … we await your orders, sir."

Jim might have swallowed his tongue. "My-my orders, Spock?"

"Yes, sir," Spock inclines his head, and then offers a test. "Unless, of course, you are relinquishing command?"

"No!" Jim says, perhaps before he has even thought it through. "No, Mr. Spock," he continues, more calmly. "I am the captain of the Enterprise."

Spock nods solemnly, glad to hear even this tentative surety in his friend's voice.

Jim sighs, then, tiredly. "You will … _help_ me, though, won't you, Spock?"

The Vulcan cocks an eyebrow. "Of course, captain. I would suggest a communication to the crew. You must inform them of the existence of an imposter aboard. We must then locate your duplicate and reconvene in the transporter room where, I trust, Mr. Scott will be waiting with answers."

Jim does not question, does not smile, does not tease Spock for his tendency to take command from his place at Jim's right hand. He simply says, "Yes, I'm sure you're right."

Spock might have frowned, but before Jim can decide, the comm at Spock's side beeps and McCoy's voice is crackling over the wire, not bothering to wait for the commander's response. "_Damnit, Spock, he's getting worse. He attacked Chekov before heading for the lower decks._"

Jim stands, his face appalled. He looks to his first officer. "I attacked a crewman? I attacked … Chekov?"

Spock stays silent, waits for his friend's next move.

Jim walks to the comm on his cabin wall. Without hesitation, he flicks it on. "Kirk to the bridge. McCoy, this is the captain speaking. You are to return to medical bay and wait. Commander Spock and I will be bringing the imposter to you there shortly. Lieutenant Uhura, you will issue a ship wide communication explaining the nature of this emergency as … _delicately_ as you can. McCoy, is Chekov alright?"

A slightly stunned silence. Then: "_Yes, sir, he's here. Managed to blacken your eye pretty good._"

Spock thinks he can hear a humorous undertone to the doctor's words.

"Chekov," the captain continues over the comm. "I'm sorry. I-I'll make it up to you."

The young helmsman's voice comes over the wire. "_Not to vorry, keptin, not to vorry._" He sounds, as always, irrationally cheerful.

Jim exhales. "I'll be waiting to hear that comm., Uhura. Kirk out."

Spock stands to face his captain, a knowing gleam in his brown eyes. Jim looks at him uncertainly, but he nods once, as if he thinks he might have done well. Spock returns the gesture, the hint of a smile in the left-hand corner of his mouth.

* * *

_A/N: Reviews are super fun, by the way..._


	3. Chapter 3

_Author's Note: Hello all. We are nearing the end of what was, originally, meant to be just a one or two shot. I think there's probably only a chapter left, with maybe an epilogue. Anyway, there's not too much to say here other than forgive this chapter being a little angstier than the other two, I promise there will be a little more humor coming up in the next installment. Thanks for reading!_

* * *

Thankfully, the corridors of the Enterprise are mostly deserted as captain and first officer make their way towards the lower decks of the ship. Jim lets Spock take the lead – a concession that does not go unnoticed by the Vulcan himself. It is unsettling to have the captain silently trailing behind him. Ordinarily the man is a constant assault upon the senses – striding ahead of Spock with sure footsteps, ever in sight; issuing orders and cracking jokes is equal measure, his voice a steady, familiarity in Spock's ears. The man who follows him now is mute, moving only when Spock moves, mirroring his first's actions, afraid to step out of the reassuring sphere of his steady influence.

Overhead, Uhura's voice can be heard delivering the captain's mandated warning to his crew. The word "imposter" rings dangerously down the empty hall, bounces off the sleek interior of Jim's ship.

"Captain?"

Jim blinks and finds that they have arrived. Spock is standing at his shoulder, an eyebrow raised in concern. "I would advise splitting up, Captain; we are likely to find the intruder in half the time."

Jim nods, once, and watches his first officer disappear around a corner without hesitation. He takes a breath, sets his phaser to stun, and makes off in the opposite direction.

It is not long before he hears footsteps. They are not Spock's, he is sure, and at first he thinks they might be a delayed echo of his own. But when he stops, they continue, and Jim stands silent and still, letting them catch up to him. When they cease, he turns slowly on his heel to discover … himself.

The sensation of vertigo is crippling and instantaneous. Jim lets his gaze fall from the crown on his counterpart's head down to the shiny boots on his feet. It is not like looking in a mirror, not at all. For while he can feel the frown etched deeply on his own forehead, his twin is smiling a crazed little smile, mischievous delight shining in his too-blue eyes.

Jim stands stock still while his counterpart circles him, chuckling in a self-satisfied manner. "Damn," he laughs, giving Jim the once over, "I look _good_."

Jim stiffens under his other self's keen observation, noting how unnerving it is to be under the scrutiny of that appraising gaze. "You have to come with me," he begins diplomatically. "We have to find a way to fix this."

Jim's "bad" half laughs obscenely in the quiet space. "You must be joking."

"No," Jim fails to find the humor, "We have to go back to the transporter room. Mr. Scott is working on a cure…" He tries to ignore the self-righteous smirk on the other Jim's face. "It's important," he tries again, lamely. "Please."

"Fuck," says his twin in disgust. "You're _pathetic_."

Jim comes up a little short, tries to begin again, but his counterpart interrupts: "No, listen, don't even bother. Why on earth would I want _you_ back up _here_?" he taps his temple, fingertips brushing the short golden hairs there. "You just ruin all the _fun_. Make me go to sleep at a '_decent hour_'," he mocks, "Don't let me eat what I want, drink what I want, fuck who I want…"

Jim recoils at the animalistic growl underlying his twin's words. He knows Spock told him that this manifestation of himself is merely lacking in his better half's more civilized inhibitions, but he cannot help but fear the idea that this depth of depravity does indeed lurk within the depths of his person.

"You can't … you can't hurt me," he raises his phaser, but his hand is shaking.

"Oh put it away," his alternate says, shaking his head as if embarrassed for his other half's weakness. "You're done here – you're no good for this ship. You can't even aim your phaser without getting all weepy. If you'd had any balls at all, you'd have shot me five minutes ago."

Jim tries to hold his gaze steady, but his eyes flicker to his own trembling hand, conceding the point. His counterpart continues:

"I'm twice the captain you are. They all know it's true. Scotty, Bones, Spock… they already know you're worthless."

A movement in the shadows over his twin's shoulder draws Jim's attention. It's his first officer, carefully approaching the place where the two Jims are engaged in their confrontation. Spock looks from one to the other, notices Jim has lowered his phaser, and raises an eyebrow inquiringly. "Captain?"

"Spock!" Jim's alternate spins in place, eyes shining a lusty shade of sapphire.

Jim feels himself tense, thinks about taking a step forward but abandons the thought before it is even fully formed.

"How nice of you to join the party," his twin chuckles darkly. He looks the Vulcan over, slowly, lingeringly, and unleashes the full force of his eyes under heavy brows, not bothering to conceal an obscene lick of his lips as he says, "I can only imagine what you're thinking, _Commander_. All the possibilities … _two_ Jim Kirks …" He lets the implication drift off into a sexually-charged silence.

Spock does not so much as blink. He looks directly past him and says, steadily, "You have wasted precious time, Captain. I must insist that you stun the imposter before he does yet further damage to the Enterprise or her crew."

Jim raises his phaser once more, but is distracted by his twin turning to smile at him through the darkness. The gleam of his white teeth in the dark is deadly and inviting both at once, and Jim falters. The imposter takes a step toward him, then another, slowly closing the gap between them.

When they are nose to nose, Spock is there. He delivers a Vulcan nerve pinch and Jim takes a startled breath as the body of his twin falls to the floor. Jim raises his gaze to look into the serious brown eyes across from him, an "I'm sorry" already forming on his tongue.

"Captain?" Spock interrupts, as if daring him to follow through with his apology – challenging him silently, forcing him to rethink his weakness, or at least the admission thereof.

Jim nods once. "Let's go, Spock," he says, and the Vulcan inclines his head in approval.

* * *

Back in the transporter room, Scotty is explaining his conclusions to a stony-faced audience.

"I think I've got all the kinks worked out," he tells his companions, "but I'd like to test my theory on the dogs first. It had something to do with the yellow debris brought back by Fisher on his uniform. The magnetic properties made the transporter signals a little wonky. I think," he holds up a finger, suspending doubt until he'd finished, "we might try beaming the dogs back _together_ and _hopefully_ the return journey will reverse the split."

Jim, Spock, and Bones stand quietly, unable to offer a better solution.

And so Scotty begins his preparations and Bones sedates the animal's vicious twin and the dogs are placed on a single transporter pad. The beam activates and the dogs disappear. The room is hushed for a minute, two minutes, three…

When Scotty reverses the transport, there is a moment of suspended hope. There is only a single dog where before there had been two, lying motionless on the transporter pad. But McCoy puts two fingers to its furry neck and looks up at his companions sadly. "It's dead," he says, and his blue eyes are locked on Jim.

Before the captain can speak, however, Spock is at his elbow. The voice of reason, pulling him back from the brink of despair. "The animal has died of shock, Dr. McCoy," he argues. "Unaware of what was happening to him, the creature's heart merely stopped."

Bones is ready with a rebuttal. "You can't know that, Spock, that's-"

"Given Mr. Scott's superior ability and his knowledge of transporter capabilities, the only radical variable-"

"At least let me do a proper autopsy on the damn dog, Spock, I-"

"The captain is in possession of a human intellect, Dr. McCoy, which the animal was not. The chances of fatality for the captain are therefore significantly reduced to approximately thirty-two point five percent."

Bones stares at the Vulcan in disbelief. "Right," he nods, irate. "Fine. Jim, you're the captain, the final decision is yours."

Spock levels his gaze on Jim as well.

And Jim visibly pales, staring at the body of the dead animal at his feet.

He looks to Dr. McCoy, at Bones, his best friend. The doctor's eyes are worried and the lines around his mouth stand out, evidence of his compassion. Jim knows he's scared, knows that he will not put Jim's life at risk with only a two-thirds chance of survival.

And Jim looks to his first officer. Spock, standing coldly with his hands clasped behind his back. He knows no one else can see it, but Jim can – that flicker of fear behind dark eyes. Spock is as afraid for his captain as Bones, perhaps more. But there is something else there that is absent in the doctor. A test – a challenge. He is pushing Jim, as he always does, to face this obstacle, to surmount it. As well as an unwavering trust that Jim will do so, will succeed.

Jim's gaze trips from one man to the other, but his brain feels hazy and his heart is heavy. "I-I can't. I can't decide," he mumbles lamely. "Please help me." He looks to Spock with this last.

And Spock's eyes take him in, unblinking. They both recall the Vulcan's promise to "help" Jim earlier in the day, and Spock's gaze is soft, as if he had foreseen this precise moment.

"We cannot help you, Jim," he says softly, gently reminding Jim of something long forgotten. "The decision is yours alone; you _are_ the captain."

And Jim knows – and Spock knows he knows – that this denial of help _is_ the help Jim is asking for, _had_ asked for before he could have even known…

He nods solemnly and offers Bones an apologetic looks before turning to Spock with a smile that is just slightly off-center. "Let's do this," he says. His Vulcan offers an approving nod in return.


	4. Chapter 4

_Author's Note: Soooo sorry about the delay on the conclusion here. Forgive me? I don't have too much to say, really, just that this has been quite an interesting endeavor, fitting TOS plotlines to reboot characters. Keep an eye out, because this is definitely something I'll be trying again. Other than that – thank you, everyone, for your wonderful words of encouragement and support, and I hope you enjoy the final installment!_

* * *

It should be easy. Jim knows this. He is the youngest starship captain in history – the leader of the remarkable _Narada_ crew – Starfleet's own golden boy. Perhaps even more importantly, he is Jim T. Kirk, winner of bar brawls, daredevil driver of classic cars, woo-er of women…

And yet, Jim is slowly coming to realize that the man responsible for such an impressive resume of bad-assery is the man lying in the bed beside him. So it is _not_ easy, no, convincing _that _man to give up his freedom and chain himself once more to the rational, timid, self-deprecating man he is now.

The captain studies his other half. He looks oddly asymmetrical, somehow disfigured. His breathing is shallow and his hands are shaking. He will not look at Kirk, but keep his eyes resolutely fixed on the ceiling.

"He's dying, Jim."

It's Bones, leaning against the doorframe with his arms crossed over his chest in the classic Bones tell that shouts: "_I'm trying to look as casual as possible because I don't really want you to know that I'm gosh darn terrified right now_."

Jim lifts a wary eyebrow. "Dying? Can I … can we live if the other ones dies?"

Bones' frown deepens minutely. "I don't know, Jim."

Jim looks back to his imposter, resolve fading fast. It's difficult to stick to his guns without Spock there to help him. "I don't even know if I _want_ him back," he mumbles miserably. "He's like an animal. He doesn't care about _anything_." A pause. "But … without him… I don't know, without him there's nothing."

Bones heaves a sigh and lets his arms drop. "Aw hell, Jim, that's not true."

A skeptical eyebrow raise.

"Well, not _all_ true," the doctor clarifies. "You have your intelligence. Something obviously lost on your … well, this guy. Look at him. He's terrified. But you – you managed to overcome that fear. That's why you're here. But you're right – the power to command … well, that's him."

Jim nods once, tells Bones to carry on with the autopsy of the space dog. He knows there isn't time – that Bones won't be able to gather anything conclusive in the short amount of time allotted him. Sulu and the others will freeze to death first. But he needs a moment. Just a moment to _think_.

His other half is trembling more violently now. They lock eyes and Jim finds that Bones' analysis was entirely accurate. The blue eyes looking back into his are filled with an emotion Jim himself has never felt: pure, helpless, hopeless fear. Without thinking, Jim takes his hand. Squeezes it once. "It's okay, he begins, "it's all going to be okay…" His compassion is so great that he releases the others' restraints, reaches out his other hand to embrace the wretched creature.

But he has made a fatal error. He has forgotten that as far as compassion goes, his twin has none. The other Jim shoots from the bed with lightning speed, all tears faded in the light of a possible escape. The captain has mere seconds to contemplate his mistake before he is knocked out cold.

* * *

Lieutenant Uhura takes a moment to reevaluate what she has just heard. She doubts the evidence of her own ears. "I-I'm sorry, Captain, what did you say?"

"I _said_, 'Warp five. Set a course for Starbase Seven'. Are you having trouble hearing, Lieutenant? Should I call for your relief?"

The young woman's eyes are so large and round that the captain's reflection can be seen in them. "But, sir … Sulu and the others … what about-"

The captain slams a fist on the console beside him. "It's too late for them!" he yells. "They're dead! Warp five _now_!"

Uhura hesitates, her fingers over the controls. She knows about the "imposter" – heard the communication along with the rest of the crew.

"Sir-"

But the captain strikes her with a fierce backhand that sends her out of her chair. She hears a collective gasp from the rest of the bridge crew, even an outraged cry from Chekov.

And then, a familiar voice from the back of the room.

"Stop this _now_!"

And now there are _two_ captains. The captain who struck Uhura, now occupying the Lieutenant's seat – and the captain standing in the doorway, Bones at his shoulder, radiating outrage at the attack on one of his crew.

The two men glare at each other across the room and a moment of silence engulfs the bridge of the _Enterprise_, leaving nothing but the _blip-blip_ of the instruments to be heard.

But with Uhura bleeding on the floor with the imposter cowering in her chair, and Jim standing tall at the entrance to the bridge, there is little doubt as to who the captain of this ship truly is.

Jim takes a step forward and extends a hand. "You will come with me now," he commands. "This is over."

* * *

In the end, the imposter did _not_ come quietly. But then, no one had really expected him to. They dragged him kicking and screaming to the transporter room. He sobbed as Jim held him in place, gnashed his teeth when Spock locked eyes with Jim and issued the order to energize.

But the captain remained calm, took a deep breath and nodded just once before disintegrating before all their eyes.

In the end, even Spock was surprised to find that their plan had worked – that the man who beamed back was indeed his captain, James T. Kirk, restored to his former self and in full health and humor.

But when Jim questioned him on his unwavering faith in Jim's abilities, Spock's eyebrows came together sadly and he offered an answer Jim never could have predicted.

"You forget, Captain, that being split between two selves is no mere theory for me. I have a human half and an alien half – the two constantly at war with one another. I survive because my intelligence wins over both and allows me to live as a single, whole being. It was only logical to assume that you would succeed in surmounting similar obstacles."

In the end, Sulu and the others were beamed back aboard safely and treated for only minor cases of hypothermia. Ensign Chekov made the entire crew laugh when he tackled Sulu to the ground in his boyish delight at the pilot's rescue, and order seemed to be restored to the _Enterprise_ and her crew.

In the end, the captain stood on the bridge with Dr. McCoy and Commander Spock and managed to laugh.

"Thank you," he said to his friends, eyes shining with genuine gratitude. "From both of us."


End file.
